Abstract: Conventional agricultural irrigation pumping stations are generally plagued by single functionality, large land occupation, high energy consumption, and poor adaptability to fragmented small scale paddy fields. In most rice growing regions, irrigation and drainage systems rely on separate sets of equipment, leading to messy layout, low utilization efficiency, and increased infrastructure costs. Moreover, specialized integrated irrigation drainage pumping equipment that can meet the full cycle water management requirements of rice at different growth stages remains extremely scarce, which severely restricts the development of water saving agriculture and the modernization of smallholder farmland water conservancy facilities. To overcome these prominent technical bottlenecks and application limitations, this study focuses on the actual water supply and drainage demands of small and medium sized paddy fields, and proposes a compact, high efficiency, and easy to deploy small scale two way flow passage pumping station. The core objectives are to realize stable bidirectional water conveyance without impeller reversal, improve overall hydraulic performance, reduce land occupation and energy loss, and provide a practical and reliable integrated equipment solution for precise water management in modern paddy fields.The pumping station adopts an integrated modular outdoor cabinet structure with a footprint of only 2.79 m², which ensures easy installation, migration, and maintenance while minimizing occupation of cultivated land. It achieves flexible and reliable switching among four operating modes—pumping irrigation, pumping drainage, gravity irrigation, and gravity drainage—through the coordinated regulation of a unidirectional impeller and five groups of motorized valves, thus avoiding the efficiency decline and mechanical wear caused by frequent impeller reversal. Numerical simulations were carried out using ANSYS 2024 CFX software with the Shear Stress Transport (SST) turbulence model, and grid independence verification was completed with approximately 5.88 million elements to guarantee computational accuracy and reliability. Internal flow field characteristics were comprehensively analyzed based on velocity vector contours, static pressure contours, external characteristic curves, and quantitative hydraulic loss decomposition. In addition, theoretical calculations of hydraulic loss based on the Colebrook White formula and field validation experiments in actual paddy fields were combined to verify simulation accuracy and evaluate real world operational stability and efficiency.Numerical results indicate that the pumping station achieves a peak irrigation efficiency of 59.46% at the flow rate of 28 m³/h, with a head of 16.40 m and shaft power of 2.20 kW. Under the same flow condition, the drainage efficiency reaches 50.20%, with a head of 14.76 m and shaft power of 2.23 kW. Compared with the irrigation condition, the drainage mode shows significantly stronger flow turbulence, more intensive vortex structures, and higher hydraulic loss, which is mainly caused by the mismatch between inflow direction and impeller inlet angle, leading to premature flow separation, increased local flow resistance, and aggravated energy dissipation. Hydraulic loss analysis reveals that local resistance loss accounts for more than 80% of the total hydraulic loss under irrigation and over 92% under drainage, confirming that local pipe fittings, turning sections, and blind tubes are the dominant sources of energy consumption. Field experimental results demonstrate that the pumping station operates stably within the flow range of 22.7～40.8 m³/h. At the optimal operating point of 28 m³/h, the measured irrigation efficiency is 56.67% and drainage efficiency is 52.15%, with relative errors of 4.92% and 3.74% respectively compared with numerical simulation values, showing excellent consistency between simulation and test. The pumping station can complete irrigation or drainage operation for 0.2 hm² of paddy field within 3 hours, fully satisfying the rapid and efficient water regulation demands of small scale farmland.The developed two way flow passage pumping station features compact structure, flexible mode switching, stable operation, and high efficiency, which can effectively meet the integrated irrigation drainage requirements of paddy fields during the whole growth period. Further performance improvement should focus on flow path optimization, local resistance reduction, valve layout adjustment, and inlet impeller matching design. This study not only reveals the internal flow characteristics and hydraulic loss mechanism of the two way flow passage under bidirectional operation, but also provides key technical support and engineering reference for the structural optimization, performance upgrading, and large scale popularization of small scale integrated irrigation drainage equipment. The research outcomes contribute to promoting water saving agricultural development, improving farmland water management intelligence, and supporting the high quality development of modern rice cultivation.